What Lymph Does
The 4 Main Roles of the Lymphatic System
1) Return of Fluid to Circulation (Back to Our Bloodstream)
Lymph, like blood, flows through special vessels in the body.
Whereas blood flows through blood vessels (veins, arteries, capillaries), lymph flows through lymphatic vessels.
One of the main jobs of the lymphatic vessels is to provide return transport of fluid that is dropped off at our tissues by our blood stream.
The Lymphatic System
The Flow of Fluids Through the Body
The process works like this: blood containing oxygen and many nutrients is pumped out towards our extremities (arms/hands, legs/feet) through arteries by the heart.
When the blood gets near to the surface of tissues, the arteries shrink way down to tiny little web-like structures called capillaries. At the capillaries fluid and nutrients from the blood seep out of the capillaries and work their way into the surrounding tissues.
What doesn’t seep out of the capillaries continues along the same path in the circulatory system through the veins and makes its way back to the heart.
How Fluid Becomes Lymph
The fluid that did seep out of the capillaries (called “interstitial fluid” at this stage) doesn’t re-enter the capillaries and return through the veins as was once thought.
Instead, it is picked up from tissues by the lymphatic system (where it is then called “lymph”) and is transported back to the circulatory (blood) system. It is all dumped back into the big veins that are found under our collar bones that go right into the heart.
When this return of fluid fails to happen because of damage to the lymphatic system through surgery to remove lymph nodes, an accident, or chemotherapy, the resulting backup of fluid leads to a condition known as Lymphedema.
2) The Lymphatic System is a Major Part of Our Immune System
The Lymphatic System is a very important part of our immune system, and it is where white blood cells (called “lymphocytes”) hang out waiting for invaders.
You know when the white blood cells are hard at work because your “glands” swell in your neck when they have latched onto pathogens, like bacteria or viruses. The swollen “glands” are where invading pathogens are trapped and broken down.
Technically speaking, the swollen areas on your neck are lymph nodes, not glands. (Glands are something entirely different, but having “swollen glands” is what we call it when our lymph nodes swell, so that helps you to best understand if I referred to them initially as such.) You might also feel swollen lymph nodes in your armpits and the crease of your hip.
In addition to the lymph nodes that filter lymph, the spleen, the thymus gland (this one is actually a gland), the tonsils, the appendix, and some special tiny structures in the intestines (known as lacteals) are also part of the lymphatic system.
What Else Does Lymph Do?
3) Nutrient Absorption & Distribution
The lymphatic system is critical to our absorption and distribution of fat and fat-soluble vitamins. It absorbs helps to deliver these large molecules that are too big to travel through blood capillaries from the intestines to the tissues. Without this system, we would suffer from malnutrition.
Nutrient Uptake in the Intestines
4) Waste Transport
Like the circulatory system (blood, heart, vessels), the lymphatic system is a one-way system that helps move waste products away from our tissues and to the organs that help to eliminate them from the body (kidney, liver, colon, skin, and lungs).